The present invention relates to chip components such as chip inductors or chip beads, or oxide magnetic materials to be used to components of shielding electromagnetic wave such as bulk typed inductors and a method of producing the same, as well as bulk typed coil components or laminated coil components using such oxide magnetic materials and a method of producing the same, and more specifically relates to oxide magnetic materials enabling to be fired at a melting point or lower of Ag used to internal conductors of the chip components, and a method of producing bulk or chip typed inductors using oxide magnetic materials having excellent high frequency characteristic.
Recently, remarkable developments of electronic or communicating devices construct new industrial structures, basing on miniaturization of electronic components, making them thin films and improvements of mounting them onto apparatus, but such developments of the industrial developments have had double sided tendency causing social problems by inducing new problems, that is, environmental and communicating troubles negligible at past ages.
In particular, because wireless-communicating devices has generally been used and electromagnetic circumstances are worsen, an electromagnetic interference regulation of each country has been strengthened. For example, it has been demanded to develop elements for canceling harmful electromagnetic waves (EMI/EMC) and components therefor have rapidly increased, while concurrently the complication of functions as to magnetic and temperature characteristics, high integration and wide frequency ranges have been developed toward high efficiency.
Incidentally, application ranges of the oxide magnetic materials to be used as blank materials of electronic components for elements canceling electromagnetic troubles, or used to components such as transformers for electric power are fractionalized per characteristic, for example, per frequency ranges. Additionally, with respect to production methods, studies of methods producing multilayer components have been actively advanced from a conventional powder metallurgical production method and reduced to practice, and today anchored as production techniques of miniaturized chip components in production fields of ceramic electronic components.
In general, the oxide magnetic materials to be used to chip inductors, chip LC filters and chip transformers necessitate high inductance, and such oxide magnetic materials are enumerated as Mnxe2x80x94Zn ferrite, Ni ferrite, Nixe2x80x94Zn ferrite or Nixe2x80x94Cuxe2x80x94Zn ferrite.
In a case of Mnxe2x80x94Zn ferrite, since permeability is high and electric power loss is very little, it is used to magnetic core materials of transformers for electric power source or core materials of filters for electric power lines, but since the high frequency characteristic is low, it is disadvantageously difficult to apply Mnxe2x80x94Zn ferrite in frequency ranges of 1 MHz or higher. At the present time, as the magnetic cores to be used in such high frequency ranges, there are applicable Ni ferrite, Nixe2x80x94Zn ferrite or Nixe2x80x94Cuxe2x80x94Zn ferrite.
On the other hand, a prior art method of producing the above mentioned oxide magnetic materials is carried out at about 1000 to 1400xc2x0 C. for 1 to 5 hours in the firing procedure. Ag electrode is usually used to internal conductors of the electronic components such as the laminated chip inductors, but the baking temperature as mentioned above exceeds a melting point (960xc2x0 C.) of Ag as the internal conductor, and the conventional method is involved with a problem that since Ag is melted and diffused in components produced under a very high temperature condition, a loss in the high frequency is very much, and therefore it is very difficult to realize a required inductance.
As an additive to be used for providing chips where the firing temperature is lowered so that the loss is little, CoO is ordinarily used as proposed in JP-A-9-63826. But CoO deteriorates the temperature characteristic of inductance in proportion to its adding amount and has a problem of affecting influences to reliability of products.
Accordingly, for solving the above mentioned problems involved with the prior art, it is an object of the invention to provide Nixe2x80x94Cuxe2x80x94Zn based oxide magnetic materials, and chip components using the same, as well as a method of producing oxide magnetic materials and a method of producing chip components by adding such additives where if reacting with main components of a base material, the electromagnetic characteristic is deteriorated at minimum and the temperature characteristic of the inductance is deteriorated at minimum, whereby not only the internal conductor is stabilized at very low baking temperatures, but also the characteristics in the high frequency zones of 100 MHz or higher are excellent.
For accomplishing the above mentioned object, the invention is to offer the oxide magnetic materials of the following (1) to (9) and the chip components using the oxide magnetic materials as well as the method of producing the oxide magnetic materials and the method of producing the chip components.
(1) The oxide magnetic materials are composes, Fe2O3: 35.0 to 51.0 mol %, CuO: 1.0 to 35.0 mol %, NiO: 38.0 to 64.0 mol %, and ZnO: 0 to 10.0 mol % (including 0%).
(2) The oxide magnetic materials as set forth in the above (1), contains Ca: 0.3 wt % or lower (not including 0%).
(3) The oxide magnetic materials as set forth in the above (2), contains CoO: 0.7 wt % or lower (not including 0%).
(4) A method of producing oxide magnetic materials is characterized in that oxide magnetic materials composed of, Fe2O3: 35.0 to 51.0 mol %, CuO: 1.0 to 35.0 mol %, NiO: 38.0 to 64.0 mol %, and ZnO: 0 to 10.0 mol % (including 0 mol %), are contained with Ca3 (PO4)2 0.5 wt % (not including 0%), and the oxide magnetic materials are fired.
(5) The method of producing oxide magnetic materials as set forth in the above (4), is characterized by containing CoO: 0.7wt % or lower and, the oxide magnetic materials are fired.
(6) Chip components are characterized in that bulk typed coil components are structured by using sintered bodies of oxide magnetic materials containing, Fe2O3: 35.0 to 51.0 mol %, CuO: 1.0 to 35.0 mol %, NiO: 38.0 to 64.0 mol %, and ZnO: 0 to 10.0 mol % (including 0%), or sintered bodies of the magnetic materials further containing Ca 0.3 wt % or lower (not including 0%), or containing Ca 0.3 wt % or lower (not including 0%) and CoO 0.7 wt % or lower (not including 0%).
(7) Chip components are characterized in that laminated coil components are structured by using sintered bodies of oxide magnetic materials containing, Fe2O3: 35.0 to 51.0 mol %, CuO: 1.0 to 35.0 mol %, NiO: 38.0 to 64.0 mol %, and ZnO: 0 to 10.0 mol % (including 0%), or sintered bodies of the oxide magnetic materials further containing Ca 0.3 wt % or lower (not including 0%), or containing Ca 0.3 wt % or lower (not including 0%) and CoO 0.7 wt % or lower (not including 0%), and said oxide magnetic materials having electrically conductive layers in the sintered bodies.
(8) The chip components as set forth in the above (7) are characterized in that an internal conductor is composed of a conductor having main components of Ag or Agxe2x80x94Pd alloy.
(9) A method of producing chip components, using sintered bodies of oxide magnetic material containing, Fe2O3: 35.0 to 51.0mol %, CuO: 1.0 to 35.0 mol %, NiO: 38.0 to 64.0mol %, and ZnO: 0 to 10.0 mol % (including 0%), or sintered bodies of the magnetic materials further containing Ca 0.3 wt % or lower (not including 0%), or containing Ca 0.3 wt % or lower (not including 0%) and CoO 0.7 wt % or lower (not including 0%), and employing in the sintered bodies, as electrically conductive layers or electrical conductors, conductors having main components of Ag or Agxe2x80x94Pd alloy, is characterized by baking ground oxide magnetic materials and the internal conductors at 880 to 920xc2x0 C.
Thus, the following working effects can be exhibited.
(1) It is possible to obtain the oxide magnetic material which is small in an initial permeability, large in a sintered density, little in eddy current loss, and available in firing at low temperature in the high frequency range of 100 MHz or higher where the inventive products are used.
(2) It is possible to obtain the oxide magnetic material which is low in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance by adding Ca 0.3 wt % or lower.
(3) It is possible to obtain the oxide magnetic material which is small in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance by adding Ca 0.3 wt % or lower and further CoO 0.7 wt % or lower.
(4) It is possible to obtain the oxide magnetic material which is low in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance by adding Ca3 (PO4)2 0.5 wt % or lower.
(5) It is possible to obtain the oxide magnetic material which is low in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance by adding CoO 0.7 wt % or lower other than Ca3 (PO4)2 0.5 wt % or lower.
(6) As the chip component is composed with the oxide magnetic material which is low in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance, it is possible to offer the chip component which is excellent in these respective characteristics.
(7) As the laminated coil component is composed with the oxide magnetic material which is low in the initial permeability, large in the sintered density, excellent in the temperature characteristics of the inductance, and low at the baking temperature, it is possible to offer the laminated component which is excellent in these respective characteristics and superior in a quality factor Q.
(8) As the chip component is composed with the conductor where the internal conductor has the main component of Ag or Agxe2x80x94Pd alloy, using the oxide magnetic material which is low in the initial permeability, large in the sintered density, excellent in the temperature characteristics of the inductance, and low at the baking temperature, it is possible to offer the chip component which is excellent in these respective characteristics and superior in a quality factor Q.
(9) As the chip component is composed by the steps of using the oxide magnetic material which is low in the initial permeability, large in the sintered density, and excellent in the temperature characteristics of the inductance, and which has the conductor as the internal conductor of the main component being Ag or Agxe2x80x94Pd alloy, and baking at 880 to 920xc2x0 C., it is possible to offer the chip component which is excellent in these respective characteristics and superior in a quality factor Q.